Here's what the calculator looks like:

You can't use it here, not until I learn PHP (whatever exactly that is :p) but if you have a spreadsheet program such as Excel or Open Office Calc you can download this sheet and enter quantities to calculate your order total. (You may need to "save as..." before you can enter quantities.)

As an alternative to money, I also accept fatally torn or stained fleece clothing or blankets, cotton pajamas, silk ties... anything that's beyond what a thrift store would sell but still has usable fabric.